But Trump was required to note the transaction as a liability the prior year and failed to do so.

OGE's acting director, David Apol, sent a letter to Deputy Attorney General Rod Rosenstein along with the financial disclosure, notifying the Justice Department of the Cohen payment. Cohen and Trump are now battling Clifford in California federal court, where she is suing to have the NDA nullified. If they conclude it was made with the intention of influencing the presidential campaign - making it an effective political contribution - it would violate election law, which caps individual donations to federal candidates at $5,400 per election cycle. "If the [Justice] Department is not already investigating the president's failure to disclose the loan a year ago, it should open an investigation immediately".

Now, legal experts are saying that Trump needs to declare any payments related to Daniels because payments made to the adult film star in 2016 could possibly be violations of campaign finance law.

U.S President Donald Trump looks on during a meeting with South Korean President Moon Jae-in in the Oval Office, on June 30, 2017.

Trump's lawyer Michael Cohen, declared earlier this year that it was he and he alone who had arranged the payment for Daniels, and this admission caused Daniels' attorney, Michael Avenatti, to pounce.

Trump had previously denied knowing anything about the payment, but his lawyer, Rudy Giuliani, recently revealed that Trump knew about the payment and had reimbursed Cohen through monthly retainer payments.

First lady Melania Trump's income, royalties from Getty Images photographs, are also listed in the 2018 report.

Other properties have not fared as well, including Trump National Doral, a golf resort near Miami, which is Trump's biggest cash flow generator.

Trump's Mar-a-Lago resort in Florida, which the president frequents in the winter months, saw revenues of $25.1 million.